package com.elves.auth.util;

import org.apache.tomcat.util.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * Created by Eleven on 2022/10/28
 */

public class RSAUtil {

    private static final String algorithm = "RSA";

    /**
     * 构建RSA密钥对
     *
     * @return 生成后的公私钥信息
     */
    public static RsaKeyPair generateKeyPair() throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(algorithm);
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();
        String publicKeyString = Base64.encodeBase64String(publicKey.getEncoded());
        String privateKeyString = Base64.encodeBase64String(privateKey.getEncoded());
        return new RsaKeyPair(publicKeyString, privateKeyString);
    }

    /**
     * 公钥加密
     *
     * @param publicKeyString 公钥
     * @param text            待加密的文本
     * @return 加密后的文本
     */
    public static String encryptByPublicKey(String publicKeyString, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyString));
        KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }

    /**
     * 公钥解密
     *
     * @param publicKeyString 公钥
     * @param text            待解密的信息
     * @return 解密后的文本
     */
    public static String decryptByPublicKey(String publicKeyString, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyString));
        KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }

    /**
     * 私钥加密
     *
     * @param privateKeyString 私钥
     * @param text             待加密的信息
     * @return 加密后的文本
     */
    public static String encryptByPrivateKey(String privateKeyString, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyString));
        KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }


    /**
     * 私钥解密
     *
     * @param privateKeyString 私钥
     * @param text             待解密的文本
     * @return 解密后的文本
     */
    public static String decryptByPrivateKey(String privateKeyString, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyString));
        KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Cipher cipher = Cipher.getInstance(algorithm);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        System.out.println("::::::::::::::::::"+text);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }


    public static void main(String[] args) throws Exception {
        RsaKeyPair rsaKeyPair = null;
        try {
            rsaKeyPair = RSAUtil.generateKeyPair();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        System.out.println("公钥：");
        System.out.println(rsaKeyPair.getPublicKey());
        System.out.println("私钥：");
        System.out.println(rsaKeyPair.getPrivateKey());
        String phone = "abcd1233";
        //公钥加密，私钥解密
        System.out.println("公钥加密，私钥解密");
        String phoneRsa = RSAUtil.encryptByPublicKey(rsaKeyPair.getPublicKey(), phone);
        System.out.println("加密后：" + phoneRsa);
        String phoneRsa2 = RSAUtil.decryptByPrivateKey(rsaKeyPair.getPrivateKey(), phoneRsa);
        System.out.println("解密后：" + phoneRsa2);
        //私钥加密，公钥解密
//        System.out.println("私钥加密，公钥解密");
        System.out.println("私钥签名，公钥验签");
        String phoneRsa3 = RSAUtil.encryptByPrivateKey(rsaKeyPair.getPrivateKey(), phone);
        System.out.println("加密后：" + phoneRsa3);
//        phoneRsa3 = phoneRsa3.substring(0, phoneRsa3.length() - 2);// 测试完整性, 删除2字符 是否还能解密
        String phoneRsa4 = RSAUtil.decryptByPublicKey(rsaKeyPair.getPublicKey(), phoneRsa3);
        System.out.println("解密后：" + phoneRsa4);
    }

    public static class RsaKeyPair {
        private String publicKey;
        private String privateKey;
        public RsaKeyPair(String publicKey, String privateKey) {
            this.publicKey = publicKey;
            this.privateKey = privateKey;
            System.out.println("publicKey::"+publicKey);
        }
        public String getPublicKey() {
            return publicKey;
        }
        public void setPublicKey(String publicKey) {
            this.publicKey = publicKey;
        }
        public String getPrivateKey() {
            return privateKey;
        }
        public void setPrivateKey(String privateKey) {
            this.privateKey = privateKey;
        }
    }
}